CN107352981B

CN107352981B - Corundum-mullite low-heat-conductivity high-strength wear-resistant castable for CFB boiler feed back device

Info

Publication number: CN107352981B
Application number: CN201710566855.4A
Authority: CN
Inventors: 陈松林; 俞小平; 王俊涛; 胡建辉; 袁林; 俞洪芳; 郭良君; 邵学军; 邵一平
Original assignee: Ruitai Technology Co ltd; Yixing Ruitai Refractory Material Engineering Co ltd
Current assignee: Ruitai Technology Co ltd; Yixing Ruitai Refractory Material Engineering Co ltd
Priority date: 2017-07-12
Filing date: 2017-07-12
Publication date: 2020-07-07
Anticipated expiration: 2037-07-12
Also published as: CN107352981A

Abstract

The invention relates to a corundum-mullite low-heat-conductivity high-strength wear-resistant castable for a CFB boiler feedback device, belonging to the field of inorganic non-metallic material subject refractory materials. The main raw materials comprise waste high-aluminum electroceramics, corundum, cubic boron nitride and titanium carbide. Waste high-aluminum electric porcelain and corundum are used as aggregate, cubic boron nitride fine powder and titanium carbide are used as fine powder, an alumina hollow sphere is added to reduce thermal conductivity, and rho-Al is used₂O₃Is prepared from the binding agent through strong stirring and packing. The castable disclosed by the invention is low in production cost, high in strength, good in wear resistance, low in heat conductivity, long in service life in a feed back device of a CFB (circulating fluid bed) boiler, and beneficial to heat preservation and energy conservation of the feed back device.

Description

Corundum-mullite low-heat-conductivity high-strength wear-resistant castable for CFB boiler feed back device

Technical Field

The invention relates to a corundum-mullite low-heat-conductivity high-strength wear-resistant castable for a CFB boiler feedback device, belonging to the field of inorganic non-metallic material subject refractory materials.

Background

The CFB boiler has the advantages of wide fuel adaptability, high combustion efficiency, large load regulation, direct desulfurization in the bed, low NOx emission, simple fuel preparation system, easy realization of comprehensive utilization of ash slag and the like, and is widely applied to steam production, heat supply, cogeneration and power station boilers. The return channel of the return device of the CFB boiler is a U-shaped body, particles in the boiler are in a strong fluidization state, and the return device is strongly washed by high-temperature materials, so that the return device is an important part directly related to the combustion of the boiler, the temperature of superheated steam and load, and is also a part which is easily worn and damaged frequently. In addition, the thermal conductivity coefficient of the currently adopted alumina high-alumina wear-resistant castable is higher (2-4 W.m)^-1·K^-1) The heat loss is serious, which is not beneficial to energy saving. Therefore, the development of a new functional material with high strength, good wear resistance and low heat conduction is one of important methods for solving the problems of short service life of a feed back device of a CFB boiler, large heat dissipation and energy conservation.

Disclosure of Invention

The invention discloses a corundum-mullite low-heat-conductivity high-strength wear-resistant castable for a CFB boiler feed back device, which is prepared from the main raw materials of waste high-aluminum electroceramics, tabular corundum, cubic boron nitride, titanium carbide and rho-Al₂O₃The formula is as follows by mass percent:

26-50% of waste high-aluminum electroceramic with particle size of 7-1 mm

5-20% of waste high-aluminum electric porcelain with the granularity of 3-1 mm

5 to 18 percent of corundum with the granularity of 1 to 0.088 mm

4 to 9 percent of cubic boron nitride powder

4 to 6 percent of titanium carbide powder

12-20% of alumina hollow spheres

ρ-Al₂O₃5~18%

On the basis of the raw materials, allyl polyoxyethylene ether maleic anhydride is added as a water reducing agent; further, the addition amount of the additional allyl polyoxyethylene ether maleic anhydride is 0.1-0.15%;

the grain size of the cubic boron nitride powder is less than or equal to 0.044 mm; the granularity of the titanium carbide is less than or equal to 0.044 mm; the spherical diameter of the alumina hollow sphere is less than or equal to 0.5 mm.

The preparation method comprises the following steps: the raw materials are mixed and ground uniformly by strong force to prepare the low-heat-conductivity high-strength wear-resistant castable for the CFB boiler feed back device, and the castable is packaged by a plastic bag in a moisture-proof way.

Construction and maintenance: the water adding amount is 3-3.5% during construction. And after the casting construction is finished and the curing is carried out for 72 hours, the mold is removed, the casting is naturally dried for 72 hours, the casting is baked for 48 hours at the temperature of 100 ℃ and 120 ℃, and then the temperature is slowly raised to the working temperature at the temperature of not more than 20 ℃ per hour.

The waste high-alumina electric porcelain and corundum are used as aggregate, the main crystal phase of the waste high-alumina electric porcelain is corundum and mullite, and the sintered material has the advantages of stable structure, stable volume, high strength and good wear resistance. The aggregate waste high-aluminum electric porcelain, corundum, fine powder cubic boron nitride and titanium carbide are high-strength wear-resistant materials, and the composite material formed by the high-strength wear-resistant materials has the characteristics of high strength and wear resistance. The cubic boron nitride and the titanium carbide are fine powder, which belong to the wear resistance of artificial synthesis, and even when the material is used at high temperature for a long time, a small amount of oxidation is generated, so that the sintering of the matrix and the aggregate is promoted, the matrix and the aggregate are combined more compactly, the overall wear resistance is improved, and the compact structure blocks further oxidation. The added alumina hollow spheres (the sphere diameter is less than or equal to 0.5 mm) have the wear-resistant characteristic, and the heat conductivity of the composite material is reduced due to the closed pore structure. With rho-Al₂O₃As a binder, rho-Al₂O₃The corundum ceramic can be hydrated to form gel at normal temperature to form low-temperature construction strength, is converted into corundum at high temperature, and is sintered and fused with waste high-aluminum electric porcelain to obtain high-temperature working strength.

The invention has the advantages that the adopted raw materials are waste materials, and the cost is low. The prepared low-heat-conductivity high-strength wear-resistant castable has high strength, good wear resistance, low heat conductivity, long service life when used in a feed back device of a CFB boiler, good heat insulation effect and contribution to energy conservation.

Detailed Description

Example 1

Selecting 50% of waste high-alumina electric porcelain with the granularity of 1-7 mm, 5% of waste high-alumina electric porcelain with the granularity of 1-3 mm, 12% of corundum with the granularity of 0.088-1 mm, 4% of cubic boron nitride powder with the granularity of less than or equal to 0.044mm, 4% of titanium carbide powder with the granularity of less than or equal to 0.044mm, 20% of alumina hollow ball with the sphere diameter of less than or equal to 0.5mm, rho-Al₂O₃5 percent of allyl polyoxyethylene ether maleic anhydride and 0.1 percent of allyl polyoxyethylene ether maleic anhydride, the raw materials are mixed and milled uniformly by strong force to prepare the low-heat-conductivity high-strength wear-resistant castable for the CFB boiler feedback device, the castable is packaged in a plastic bag in a moisture-proof way, 3 percent of water is added during construction, the castable is removed after being maintained for 72 hours after the casting construction is finished, then the castable is naturally dried for 72 hours, baked for 48 hours at 120 ℃, and then slowly heated to the working temperature at the temperature of no more than 20 ℃/hour, the performance after being calcined is 1490 ℃ × hours, the normal-temperature compressive strength is 88MPa, the permanent line change rate is-0.15 percent, and the wear resistance is³And a thermal conductivity coefficient of 1.30 W.m at 25 DEG C^-1•K^-1600 ℃ heat conductivity coefficient of 1.23 W.m^-1•K^-11100 ℃ heat conductivity coefficient of 1.02 W.m^-1•K^-1。

Example 2

Selecting 42 percent of waste high-alumina electric porcelain with the granularity of 1-7 mm, 9 percent of waste high-alumina electric porcelain with the granularity of 1-3 mm, 15 percent of corundum with the granularity of 0.088-1 mm, 5 percent of cubic boron nitride powder with the granularity of less than or equal to 0.044mm, 4 percent of titanium carbide powder with the granularity of less than or equal to 0.044mm, 16 percent of alumina hollow ball with the sphere diameter of less than or equal to 0.5mm, rho-Al₂O₃9 percent of allyl polyoxyethylene ether maleic anhydride and 0.1 percent of allyl polyoxyethylene ether maleic anhydride, the raw materials are mixed and milled uniformly by strong force to prepare the low-heat-conductivity high-strength wear-resistant castable for the CFB boiler feedback device, the castable is packaged in a plastic bag in a moisture-proof way, 3 percent of water is added during construction, the castable is removed after being cured for 72 hours after the casting construction is finished, then the castable is naturally dried for 72 hours, baked for 48 hours at 120 ℃, and then slowly heated to the working temperature at the temperature of no more than 20 ℃/hour, the performance after being calcined is 1490 ℃ × hours, the normal-temperature compressive strength is 89MPa, the permanent line change rate is-0.16 percent, and the wear resistance is³And a thermal conductivity coefficient at 25 ℃ of 1.36W.m^-1•K^-1600 ℃ heat conductivity coefficient of 1.25 W.m^-1•K^-11100 ℃ heat conductivity coefficient of 1.08 W.m^-1•K^-1。

Example 3

Selecting 34% of waste high-alumina electric porcelain with the granularity of 7-1 mm, 12% of waste high-alumina electric porcelain with the granularity of 3-1 mm, 18% of corundum with the granularity of 1-0.088 mm, 6% of cubic boron nitride powder with the granularity of less than or equal to 0.044mm, 5% of titanium carbide powder with the granularity of less than or equal to 0.044mm, 12% of alumina hollow sphere with the sphere diameter of less than or equal to 0.5mm, and rho-Al according to weight percentage₂O₃13 percent of allyl polyoxyethylene ether maleic anhydride and 0.15 percent of allyl polyoxyethylene ether maleic anhydride, the raw materials are mixed and milled uniformly by strong force to prepare the low-heat-conductivity high-strength wear-resistant castable for the CFB boiler feedback device, the castable is packaged in a plastic bag in a moisture-proof way, 3 percent of water is added during construction, the castable is removed after being cured for 72 hours after the casting construction is finished, the castable is naturally dried for 72 hours, the castable is baked for 48 hours at 120 ℃, the temperature is slowly raised to the working temperature at the temperature of no more than 20 ℃/hour, the performance after the calcination is carried out at 1490 ℃ for × hours, the normal-temperature compressive strength is 92MPa, the permanent line change rate is-0.16³And a thermal conductivity coefficient of 1.39 W.m at 25 DEG C^-1•K^-1600 ℃ heat conductivity coefficient of 1.29 W.m^-1•K^-11100 ℃ heat conductivity coefficient of 1.18 W.m^-1•K^-1。

Example 4

Selecting 30% of waste high-alumina electric porcelain with the granularity of 7-1 mm, 16% of waste high-alumina electric porcelain with the granularity of 3-1 mm, 9% of corundum with the granularity of 1-0.088 mm, 9% of cubic boron nitride powder with the granularity of less than or equal to 0.044mm, 5% of titanium carbide powder with the granularity of less than or equal to 0.044mm, 15% of alumina hollow ball with the sphere diameter of less than or equal to 0.5mm, and rho-Al according to weight percentage₂O₃16 percent of allyl polyoxyethylene ether maleic anhydride and 0.1 percent of allyl polyoxyethylene ether maleic anhydride, the raw materials are mixed and milled uniformly by strong force to prepare the low-heat-conductivity high-strength wear-resistant castable for the CFB boiler feedback device, the castable is packaged in a plastic bag in a moisture-proof way, 3.5 percent of water is added during construction, the castable is maintained for 72 hours after the casting construction is finished and then is demolded, is dried naturally for 72 hours, is baked for 48 hours at 120 ℃, is slowly heated to the working temperature at the temperature of no more than 20 ℃/hour, has the calcined performance of 1490 ℃ and × hours, and has the normal-temperature compressive strength of 89MPa, the permanent line change rate of-0.16 percent and the wear resistance of³And heat conduction at 25 DEG CCoefficient 1.38 W.m^-1•K^-1600 ℃ heat conductivity coefficient of 1.27 W.m^-1•K^-11100 ℃ heat conductivity coefficient of 1.14 W.m^-1•K^-1。

Example 5

Selecting 26 percent of waste high-alumina electric porcelain with the granularity of 7-1 mm, 20 percent of waste high-alumina electric porcelain with the granularity of 3-1 mm, 5 percent of corundum with the granularity of 1-0.088 mm, 8 percent of cubic boron nitride powder with the granularity of less than or equal to 0.044mm, 6 percent of titanium carbide powder with the granularity of less than or equal to 0.044mm, 17 percent of alumina hollow ball with the sphere diameter of less than or equal to 0.5mm, rho-Al₂O₃18 percent of allyl polyoxyethylene ether maleic anhydride and 0.1 percent of allyl polyoxyethylene ether maleic anhydride, the raw materials are mixed and milled uniformly by strong force to prepare the low-heat-conductivity high-strength wear-resistant castable for the CFB boiler feedback device, the castable is packaged by a plastic bag in a moisture-proof way, 3.5 percent of water is added during construction, the castable is maintained for 72 hours after the casting construction is finished and then is demolded, is dried naturally for 72 hours, is baked for 48 hours at 120 ℃, is slowly heated to the working temperature at the temperature of no more than 20 ℃/hour, has the calcined performance of 1490 ℃ and × hours, and has the normal-temperature compressive strength of 90MPa, the permanent line change rate of-0.16 percent and the wear resistance of³And a thermal conductivity coefficient of 1.33 W.m at 25 DEG C^-1•K^-1600 ℃ heat conductivity coefficient of 1.26 W.m^-1•K^-11100 ℃ heat conductivity coefficient of 1.12 W.m^-1•K^-1。

Table 1 shows the formulation and properties of the examples, examples 1, 2, 3, 4 and 5 all having a strength above 80MPa and a wear resistance of less than 5.0cm at 25 ℃ for × 24h³Completely meets the performance requirement in the return feeder of the CFB boiler, but leads to the thermal conductivity number of the materials of the examples (the examples are all less than 1.5 W.m) because of the introduction of the hollow alumina^-1•K^-1) And the thermal conductivity (3-5 W.m is common) of the plastic material in the common material returning device^-1•K^-1) Compared with the prior art, the material returning device is much smaller, and is beneficial to reducing heat loss in the material returning device and saving energy.

TABLE 1 example and properties of corundum-mullite low-heat-conductivity high-strength wear-resistant castable for CFB boiler recycler

Claims

1. A corundum-mullite low-heat-conductivity high-strength wear-resistant castable for a CFB boiler feed back device comprises the following raw materials in percentage by mass:

26-50% of waste high-aluminum electroceramics with the particle size of 7-1 mm;

5-20% of waste high-aluminum electric porcelain with the granularity of 3-1 mm;

5-18% of corundum with the granularity of 1-0.088 mm;

4-9% of cubic boron nitride powder with the particle size of less than or equal to 0.044 mm;

4-6% of titanium carbide powder with the granularity less than or equal to 0.044 mm;

12-20% of alumina hollow spheres with the sphere diameter less than or equal to 0.5 mm;

ρ-Al₂O₃5~18%；

0.1-0.15% of additional allyl polyoxyethylene ether maleic anhydride;

selecting raw materials according to weight percentage, mixing the raw materials, strongly mixing and grinding the mixture evenly, and carrying out damp-proof packaging by using a plastic bag;

when the castable is used, 3-3.5% of water is added to the mixed castable, casting construction is carried out, maintenance is carried out for 72 hours after the construction is finished, the castable is removed from a mold, the castable is naturally dried for 72 hours and baked for 48 hours at the temperature of 100-120 ℃, and then the temperature is slowly raised to the working temperature at the temperature of no more than 20 ℃/hour.